Oxidative stress and UV, DES compound mutation screening of high molecular weight and high- yield hyaluronic acid strain

Streptococcus equines MF003 was used as an original strain to perform H2O2 oxidative stress culture, ultraviolet radiation ( UV) and diethyl sulfate ( DES) compound mutation. After screening, a hyaluronidase deficient strain ZD-25 with high molecular weight and high- yield of hyaluronic acid was achieved. Based on shake flask fermentation, the yield of hyaluronic acid reached to 1.61 g / L and relative molecular weight of 2.13 × 106 u.Compared to the original strain, the yield and relative molecular weight were increased by 120.5% and 57.8%, respectively.The production and relative molecular weight of hyaluronic acid maintained high stability after several generation of reproduction.Furthermore, the yield of hyaluronic acid in mutant ZD-25 reached to 4.26 g / L and relative molecular weight of 2.90 × 106 u by 5L fermentation tank initial fermentation. Compared to the original strain, the yield and relative molecular weight increased 166.3% and 93.3%, respectively.